introduction to accelerators eric torrence university of oregon quartnet 2005 special thanks to...
TRANSCRIPT
![Page 1: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/1.jpg)
Introduction to Accelerators
Eric Torrence
University of Oregon QuartNet 2005
Special Thanks to Bernd Surrowhttp://web.mit.edu/8.701/www/
![Page 2: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/2.jpg)
Contents
Introduction - Terms and Concepts Types of Accelerators Acceleration Techniques Current Machines
![Page 3: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/3.jpg)
Rutherford’s Scattering (1909)
Particle Beam Target Detector
![Page 4: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/4.jpg)
Results
![Page 5: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/5.jpg)
Sources of Particles Radioactive Decays
Modest Rates Low Energy
Cosmic Rays Low Rates High Energy
Accelerators High Rates High Energy
![Page 6: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/6.jpg)
Why High Energy?Resolution defined by wavelength
![Page 7: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/7.jpg)
Energy Scales
Particles are waves
Smaller scales = HE
1 GeV (109 eV) =1 fm (10-15m)
1 MV
1 MeV electron
![Page 8: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/8.jpg)
Roads to Discovery
High Energy
High Luminosity
Probe smaller scalesProduce new particles
Detect the presence of rare processesPrecision measurements of fundamental parameters
![Page 9: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/9.jpg)
Cross-section
Area of target
Measured in barns = 10-24 cm2
Cross-section depends upon process
Hard Sphere -
1 mbarn = 1 fm2 - size of proton
about 16 pb (others fb or less)
technically infinite (E field)
![Page 10: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/10.jpg)
Luminosity
Intensity or brightness of an accelerator
Events Seen = Luminosity x cross-section
In a storage ring
Rare processes (fb) need lots of luminosity (fb-1)
Current
Spot size
More particles through a smaller area means more collisions
![Page 11: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/11.jpg)
Accelerator Physics for Dummies
Electric Fields Aligned with field Typically need very high fields
Magnetic Fields Transverse to momentum Cannot change |p|
Lorentz Force
![Page 12: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/12.jpg)
Types of Accelerators
Linear Accelerator (one-pass) Storage Ring (multi-turn)
electrons (e+e-) protons (pp or pp)
Fixed Target (one beam into target) Collider (two beams colliding)
![Page 13: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/13.jpg)
Circle or Line? Linear Accelerator
Electrostatic RF linac
Circular Accelerator Cyclotron Synchrotron Storage Ring
![Page 14: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/14.jpg)
Synchrotron Radiation
Linear Acceleration
Circular Acceleration
10 MV/m -> 4 10-17 Watts
Radius must grow quadratically with
beam energy!
![Page 15: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/15.jpg)
LEP Accelerator (CERN 1990-2000) 27 km circumference 4 detectors e+e- collisions
LEPI: 91 GeV 125 MeV/turn 120 Cu RF cavities
LEPII: < 208 GeV ~3 GeV/turn 288 SC RF cavities
![Page 16: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/16.jpg)
Protons vs. Electrons
Can win by accelerating protons
But protons aren’t fundamental
Only small fraction at highest energy
Don’t know energy (or type) of colliding particles
![Page 17: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/17.jpg)
History of accelerator energies
e+e- machines typicallymatch hadron machines with x10 nominal energy
![Page 18: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/18.jpg)
Fixed TargetSLAC End Station A 196850 GeV electons
![Page 19: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/19.jpg)
Colliding BeamsDESY HERA 1990s
![Page 20: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/20.jpg)
Center of Mass EnergyTo produce a particle, you need enough energy to reach its rest mass.Usually, particles are produced in pairs from a neutral object.
To produce
requires 2x175 GeV = 350 GeV of CM Energy
Head-on collisions:
One electron at rest:
Need 30,000,000 GeV electron...
![Page 21: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/21.jpg)
Secondary Beams
Fixed-target still useful for secondary beams
NuTeV Neutrino Production
protons
pions -> muonsneutrinos
![Page 22: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/22.jpg)
Accelerator Types
Static Accelerators Cockroft-Walton Van-de Graaff Linear Cyclotron Betatron Synchrotron Storage Ring
![Page 23: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/23.jpg)
Static E FieldParticle Source
Just like your TV set
Fields limited by Corona effectto few MV -> few MeV electrons
![Page 24: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/24.jpg)
Cockroft-Walton - 1930s
FNAL InjectorCascaded rectifier chain
Good for ~ 4 MV
![Page 25: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/25.jpg)
Van-de Graaff - 1930s
![Page 26: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/26.jpg)
Van-de Graaff II
First large Van-de Graaff
Tank allows ~10 MV voltagesTandem allows x2 from terminal voltage
20-30 MeV protons about the limitWill accelerate almost anything (isotopes)
![Page 27: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/27.jpg)
Linear Accelerators Proposed by Ising (1925) First built by Wideröe (1928)
Replace static fields by time-varying periodic fields
![Page 28: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/28.jpg)
Linear Accelerator Timing
Fill copper cavity with RF powerPhase of RF voltage (GHz) keeps bunches together
Up to ~50 MV/meter possibleSLAC Linac: 2 miles, 50 GeV electrons
![Page 29: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/29.jpg)
Cyclotron
Proposed 1930 by Lawrence (Berkeley)Built in Livingston in 1931
Avoided size problem of linear accelerators, early ones ~ few MeV
4” 70 keV protons
![Page 30: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/30.jpg)
“Classic” CyclotronsChicago, Berkeley, and others had large Cyclotrons (e.g.: 60” at LBL) through the 1950s
Protons, deuterons, He to ~20 MeV
Typically very high currents, fixed frequency
Higher energies limited by shift in revolution frequency due to relativistic effects. Cyclotrons still used extensively in hospitals.
![Page 31: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/31.jpg)
Betatron
Variant to cyclotron, keep beam trajectory fixed,ramp magnetic fields instead. 25 MeV protons in 1940s.
First fixed circular orbit device...
![Page 32: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/32.jpg)
Synchrocyclotron Fixed “classic” cyclotron problem by
adjusting “Dee” frequency. No longer constant beams, but rather
injection+acceleration Up to 700 MeV eventually achieved
![Page 33: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/33.jpg)
SynchrotronsUse smaller magnets in a ring + accelerating station
3 GeV protonsBNL 1950s
Basis of all circularmachines built since
Fixed-target modeseverely limiting
energy reach
![Page 34: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/34.jpg)
Storage Rings
Two beams counter-circulating in same beam-pipeCollisions occur at specially designed Interaction Points
RF station to replenish synchrotron losses
![Page 35: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/35.jpg)
Beamline ElementsDipole (bend) magnets
Quadrupole (focusing) magnets
Also Sextupoles and beyond
![Page 36: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/36.jpg)
Largest HEP Accelerator Labs
NuTev
![Page 37: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/37.jpg)
Fermilab Tevatron
Highest Energy collider: 1.96 TeV
top quark, Higgs search, new physics
![Page 38: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/38.jpg)
SLAC - SLC and PEPII
SLAC Linear Collider (1990-1998)Z-pole, EW physics, B-physics, polarized beams
PEPII Asymmetric Storage Ring (1999-present)
3 GeV e+ on 9 GeV e-
Very high luminosity, CP Violation, B-physics, rare decays
![Page 39: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/39.jpg)
CERN Large Hadron Collider
Under construction in old LEP tunnelWill collide pp at 14 TeV (mini-SSC)Higgs, EW symmetry breaking, new physics up to 1 TeV
![Page 40: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/40.jpg)
CERN Complex
Old rings still in useMany different programs
![Page 41: Introduction to Accelerators Eric Torrence University of Oregon QuartNet 2005 Special Thanks to Bernd Surrow](https://reader030.vdocuments.us/reader030/viewer/2022032600/56649da85503460f94a95581/html5/thumbnails/41.jpg)
Proposed 1 TeV e+e- collider
Similar energy reach as LHC, higher precision